Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device includes a non-volatile memory and a logic circuit. The non-volatile memory includes a stacked structure comprising a first insulating layer, a floating gate, a second insulating layer, a control gate and a third insulating layer stacked in this order from a substrate; an erase gate line; and a word line. The logic circuit includes a field effect transistor comprising a gate electrode. The word line includes a protrusion, and a height of the protrusion from the substrate is higher than a height of the erase gate line from the substrate. The word line and the gate electrode are formed of polysilicon.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/914,485, filed Mar. 7, 2018, which is a division of U.S. patentapplication Ser. No. 15/209,370, filed Jul. 13, 2016, the entirecontents of which applications are incorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to semiconductor integrated circuits, moreparticularly to semiconductor devices including non-volatile memorycells and manufacturing processes thereof.

BACKGROUND

As the semiconductor industry introduces new generations of integratedcircuits (ICs) having higher performance and greater functionality, costreduction pressure becomes stronger. In particular, reducing a number oflithography processes has been required.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIGS. 1A-11C show exemplary views illustrating sequential processes formanufacturing a non-volatile memory according to one embodiment of thepresent disclosure.

FIGS. 12A-21B show exemplary views illustrating sequential processes formanufacturing a word line of the non-volatile memory and a gateelectrode of a logic circuit according to one embodiment of the presentdisclosure.

FIGS. 22A-28B show exemplary views illustrating sequential processes formanufacturing a word line of the non-volatile memory and a gateelectrode of a logic circuit according to another embodiment of thepresent disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.”

FIGS. 1A-11C show exemplary views illustrating sequential processes formanufacturing a non-volatile memory according to one embodiment of thepresent disclosure. FIGS. 1A, 2A, . . . and 11A show plan view (viewsfrom the above), FIGS. 1B, 2B, . . . and 11B show cross sectional viewsalong line X1-X1 in FIGS. 1A, 2A, . . . and 11A, and FIGS. 1C, 2C, . . .and 11C show cross sectional views along line Y1-Y1 in FIGS. 1A, 2A, . .. and 11A. It is understood that additional operations can be providedbefore, during, and after processes shown by FIGS. 1A-11C, and some ofthe operations described below can be replaced or eliminated, foradditional embodiments of the method. The order of theoperations/processes may be interchangeable.

FIGS. 1A-1C show a structure of a non-volatile memory area after anisolation insulating layer 15, which is called shallow trench isolation(STI) is formed. A mask layer including a silicon oxide layer 12 and asilicon nitride layer 14 is formed on a substrate 5. The silicon oxidelayer 12 is formed by thermal oxidization or chemical vapor deposition(CVD), and the silicon nitride layer 14 is formed by CVD. A thickness ofthe silicon oxide layer 12 is in a range from about 7 nm to 10 nm, and athickness of the silicon nitride layer 14 is in a range from about 40 nmto 200 nm, in some embodiments. The substrate 5 is silicon in oneembodiment. Other semiconductor materials such as SiGe, SiC, a groupIII-V semiconductor may be used as the substrate 5. After the mask layeris formed, the mask layer is patterned by lithography and etchingoperations. Then, by using the patterned mask layer as an etching mask,the substrate 5 is trench-etched to form trenches. A depth of thetrenches is in a range from about 100 nm to about 1 μm in someembodiments.

The trenches are filled with an insulating (dielectric) material 15. Oneor more layers of insulating materials such as silicon oxide, siliconoxynitride or silicon nitride, are formed by LPCVD (low pressurechemical vapor deposition), plasma-CVD or flowable CVD. The insulatingmaterial layer may be formed by one or more layers of spin-on-glass(SOG), SiO, SiON, SiOCN and/or fluorine-doped silicate glass (FSG).After forming the insulating material layer, a planarization operationincluding a chemical mechanical polishing (CMP) or an etch-back process,is performed so as to remove upper part of the insulating materiallayer, such that the STI 15 is formed. The substrate not etched, andsurrounded or separated by the STI in plan view is an active region 10,over which transistors or other semiconductor devices are formed.

After the STI 15 is formed, the silicon nitride layer 14 is removed anda first conductive material layer 19 is formed, as shown in FIGS. 2A-2C.The silicon nitride layer 14 can be removed by using H3PO4. Theconductive material, such as undoped or doped polysilicon, can be formedby CVD. A thickness of the first conductive material layer 19 is in arange from about 80 nm to 160 nm in some embodiments.

Subsequently, the first conductive material layer 19 is planarized byCMP, as shown in FIG. 3A-3C, thereby forming floating gate patterns (FGpatterns) 20 of a non-volatile memory. A width of the FG pattern 20 isin a range from about 80 nm to about 120 nm and a thickness of the FG 20is in a range from about 20 nm to about 70 nm, in some embodiments.

After the FG pattern 20 is formed, the STI 15 is recessed by using anetch-back process, as shown in FIGS. 4A-4C. An amount T1 of the recessis in a range from about 30 nm to about 100 nm in some embodiments.

After the STI 15 is recessed, a stacked layer of first insulating layerstack 22, a second conductive layer 24, a second insulating layer stackincluding insulating layers 26, 28 and 30 is formed over the FG pattern20 and the STI 15, as shown in FIGS. 5A-5C. The first insulating layerstack 22 includes a silicon oxide-silicon nitride-silicon oxide (ONO)structure, having thicknesses of about 30-50 nm, about 70-90 nm andabout 30-50 nm, respectively, in some embodiments. The second conductivematerial layer 24 is, for example, doped or undoped polysilicon having athickness of about 45 nm to about 70 nm, in some embodiments. Theinsulating layer 26 is, for example, silicon nitride having a thicknessof about 7 nm to about 10 nm, the insulating layer 28 is, for example,silicon oxide having a thickness of about 70 nm to 100 nm, and theinsulating layer 30 is, for example, silicon nitride having a thicknessof about 800 nm to about 1200 nm, in some embodiments. These layers(22-30) can be formed by CVD. The silicon oxide or nitride layers may bereplaced with silicon oxynitride, SiOCN or SiCN.

Subsequently, the stacked layer of FIGS. 5A-5C is patterned as shown inFIGS. 6A-6C by using lithography and etching operations, thereby forminga gate stack structure including an ONO layer 22 and a control gate (CG)24. As shown in FIGS. 6B and 6C, the etching is stopped at thepolysilicon layer 20.

Subsequently, as shown in FIGS. 7A-7C, the polysilicon layer 20 isrecessed by using the insulating layers 26, 28 and 30 as an etchingmask. An amount T2 of the recess is in a range from about 10 nm to about40 nm in some embodiments.

After the recess etching, first sidewall spacers (CG spacers) 32 areformed on both main side faces of the stacked gate structure, as shownin FIGS. 8A-8C. The first sidewall spacers 32 are made of, for example,one or more layers of SiN, SiO₂ and SiON, and have a thickness in arange from about 10 nm to about 40 nm in some embodiments.

Then, as shown in FIGS. 9A-9C, the polysilicon layer 20 is furtheretched by using the insulating layers 26, 28 and 30 and the firstsidewall spacers as an etching mask, thereby forming the gate stackstructure including a floating gate (FG) 20, an ONO layer 22 and acontrol gate (CG) 24. As shown in FIG. 9B, after the polysilicon layer20 is etched, spaces 20S are formed over the active regions 10, notcovered by the stacked gate structure.

Further, as shown in FIGS. 10A-10C, second sidewall spacers (FG spacers)34 are formed on both main side faces of the stacked gate structure. Thesecond sidewall spacers 34 are made of, for example, one or more layersof SiN, SiO₂ and SiON, which may be the same or different from the firstsidewall spacers 32, and have a thickness in a range from about 10 nm toabout 40 nm in some embodiments.

As shown in FIG. 10C, the gate stack structure 50 includes a siliconoxide layer 12, a floating gate (FG) 20, an ONO layer 22, a control gate(CG) 24 and an insulating layer stack including insulating layers 26, 28and 30, which are stacked in this order from the substrate 5.

Subsequently, word lines 40 and an erase gate line 42 are formed asshown in FIGS. 11A-11C. The word lines 40 and erase gate line 42 aremade of a conductive material, such as doped polysilicon. A thickness ofthe word lines 40 and erase gate line 42 is in a range from about 80 nmto about 140 nm in some embodiments.

FIGS. 12A-21B show exemplary views illustrating sequential processes formanufacturing a word line and an erase gate line of the non-volatilememory and a gate electrode of a logic circuit according to oneembodiment of the present disclosure. In one embodiment of the presentdisclosure, a semiconductor device includes a non-volatile memory areaand a logic circuit area. The semiconductor device may also include astatic random access memory (SRAM) area.

FIGS. 12A, 13A, . . . and 21A show cross sectional views in thenon-volatile memory area, and FIGS. 12B, 13B, . . . and 21B show crosssectional views in the logic circuit area. It is understood thatadditional operations can be provided before, during, and afterprocesses shown by FIGS. 12A-21B, and some of the operations describedbelow can be replaced or eliminated, for additional embodiments of themethod. The order of the operations/processes may be interchangeable.

After the gate stack structures 50 are formed as shown in FIG. 10A-10C,a third conductive material layer 100 is formed over the gate stackstructures 50 in the non-volatile memory area and over the active region10 in the logic circuit area, as shown in FIGS. 12A and 12B. A gateinsulating layer 90 is interposed between the surface of the activeregion and the third conductive material layer 100. The third conductivematerial layer 100 is, for example, doped or undoped polysilicon and hasa thickness in a range from about 60 nm to about 120 nm in someembodiments. Further, a silicon nitride layer 105 and a silicon oxidelayer 110 are formed on the third conductive material layer 100 by CVD.A thickness of the silicon nitride layer 105 is in a range from about 50nm to about 100 nm, and a thickness of the silicon oxide layer 110 is ina range from about 30 nm to about 60 nm, in some embodiments.

Next, as shown in FIGS. 13A and 13B, a mask layer 115 is formed to coverthe logic circuit area, while the non-volatile memory area is exposed.The mask layer 115 is, for example, a photo resist pattern.

While the logic circuit area is covered by the mask layer 115, thesilicon oxide layer 110 is removed in the non-volatile memory area byusing wet etching (using HF or BHF) and/or dry etching, as shown inFIGS. 14A and 14B. Subsequently, the mask layer 115 is removed.

Then, the silicon nitride layer 105 is removed from the non-volatilememory area by using H₃PO₄, as shown in FIGS. 15A and 15B.

After the silicon nitride layer 105 is removed from the non-volatilememory area, the silicon oxide layer 110 is removed from the logiccircuit area, as shown in FIGS. 16A and 16B.

Next, as shown in FIGS. 17A and 17B, a planarization material layer 120is formed over the non-volatile memory area and the logic circuit area,such that bottom portions of the gates stack structure 50 covered withthe third conductive material layer 100 are embedded in theplanarization material layer 120. The planarization material layer 120includes one or more layers of organic materials. In certainembodiments, the planarization material layer 120 includes a bottomantireflective coating (BARC) material generally used in a lithographyprocess.

After the planarization material layer 120 is formed, the thirdconductive material layer 100 is etched-back such that the thirdconductive material layer 100 is planarized and the upper portion(insulating layer stack) of the gate stack structure 50 is exposed, asshown in FIG. 18A. Subsequently, the planarization material layer 120 isremoved, as shown in FIGS. 18A and 18B.

Then, as shown in FIGS. 19A and 19B, the silicon nitride layer 105 isremoved from the logic circuit area by using H3PO4.

After the silicon nitride layer 105 is removed from the logic circuitarea, a hard mask layer 125 is formed and resist patterns 130A and 130Bare formed on the hard mask layer 125, as shown in FIGS. 20A and 20B.The resist pattern 130A corresponds to a word line in the non-volatilememory area, and the resist pattern 130B corresponds to a gate electrodein the logic circuit area. The hard mask layer 125 includes one or morelayers of silicon oxide, SiN and SiON.

By using the resist patterns 130A and 130B as an etching mask, the hardmask layer 125 is patterned, and by using the patterned hard mask layer125, the third conductive material layer 100 is patterned. After thehard mask layer is removed, a word line 100A and an erase gate line 100Care obtained in the non-volatile memory area, and a gate electrode 100Bis obtained in the logic circuit area, as shown in FIGS. 21A and 21B.

It is understood that the device shown in FIGS. 21A and 21B undergoesfurther CMOS processes to form various features such as interconnectmetal layers, dielectric layers, passivation layers, etc.

FIGS. 22A-28B show exemplary views illustrating sequential processes formanufacturing a word line of the non-volatile memory and a gateelectrode of a logic circuit according to another embodiment of thepresent disclosure. The similar or the same configurations, processes,materials and/or structures as set forth above may be employed in thefollowing embodiment, and the detailed explanation may be omitted.

FIGS. 22A, 23A, . . . and 28A show cross sectional views in thenon-volatile memory area, and FIGS. 22B, 23B, . . . and 28B show crosssectional views in the logic circuit area. FIG. 23C is a plan view. Itis understood that additional operations can be provided before, during,and after processes shown by FIGS. 22A-28B, and some of the operationsdescribed below can be replaced or eliminated, for additionalembodiments of the method. The order of the operations/processes may beinterchangeable.

After the gate stack structures 50 are formed as shown in FIG. 10A-10C,a third conductive material layer 200 is formed over the gate stackstructures 50 in the non-volatile memory area and over the active region10 in the logic circuit area, as shown in FIGS. 22A and 22B. A gateinsulating layer 190 is interposed between the surface of the activeregion and the third conductive material layer 200. The third conductivematerial layer 200 is, for example, doped or undoped polysilicon and hasa thickness in a range from about 60 nm to about 120 nm in someembodiments.

Then, as shown in FIGS. 23A and 23B, a hard mask layer including a firsthard mask layer 205 and a second hard mask layer 210 is formed on thethird conductive material layer 200. The first mask layer 205 is formedsuch that the third conductive material layer 200 formed over the gatestack structure 50 is fully embedded in the first mask layer and thefirst mask layer has a substantially planarized surface. In certainembodiments, the second mask layer is not used.

The first mask layer 205 includes one or more layers of insulatingmaterials including Si, O, N, C and/or H. The insulating materials canbe formed by LPCVD, plasma-CVD or flowable CVD, or coating photo resist.

In the flowable CVD, fflowable dielectric materials, as their namesuggest, can “flow” during deposition to fill gaps or spaces with a highaspect ratio. Usually, various chemistries are added tosilicon-containing precursors to allow the deposited film to flow. Insome embodiments, nitrogen hydride bonds are added. Examples of flowabledielectric precursors, particularly flowable silicon oxide precursors,include a silicate, a siloxane, a methyl silsesquioxane (MSQ), ahydrogen silsesquioxane (HSQ), an MSQ/HSQ, a perhydrosilazane (TCPS), aperhydro-polysilazane (PSZ), a tetraethyl orthosilicate (TEOS), or asilyl-amine, such as trisilylamine (TSA). These flowable silicon oxidematerials are formed in a multiple-operation process. After the flowablefilm is deposited, it is cured and then annealed to remove un-desiredelement(s) to form silicon oxide. In some embodiments, one or multipleanneal processes are conducted. The flowable film is cured and annealedmore than once at temperatures in a range from about 1000° C. to about1200° C. A thickness of the first mask layer 205 is in a range fromabout 200 nm to about 300 nm in some embodiments.

The second mask layer 210 includes one or more layers of silicon nitridebased material, such as SiN, SiON or SiOCN. A thickness of the secondmask layer 210 is in a range from about 30 nm to about 70 nm in someembodiments.

After the hard mask layer is formed, resist mask pattern 215A and 215Bare formed in the non-volatile memory area and the logic circuit area,respectively, as shown in FIGS. 23A-23C. FIG. 23C shows a plan view ofthe non-volatile memory area and FIG. 23A corresponds to line Y1-Y1 ofFIG. 23C.

As shown in FIG. 23C, in the non-volatile memory area, the gate stackstructures 50 and the mask patterns 215A extend in the X direction andare arranged in parallel with each other in the Y direction. The maskpatterns 215A do not overlap the gate stack structures 50 in plan view,as shown in FIG. 23C. The mask patterns 215A are formed above regionswhere word lines are to be formed. No mask pattern is formed above aregion between the gate stack structures 50, where an erase gate line isto be formed. It is noted that the layout shown in FIG. 23C is repeatedalong the Y direction, and the mask pattern 215A will be disposedbetween two gate stack structures.

A width W1 of the mask pattern 215A along the Y direction is in a rangefrom about 50 nm to about 100 nm in some embodiments. A space 51 betweenthe mask pattern 215A and the gate stack structure 50 is in a range fromabout 15 nm to about 45 nm in some embodiments.

In the logic circuit area, the mask pattern 215B corresponds to a gateelectrode of a field effect transistor (FET).

Next, as shown in FIG. 24A and 24B, by using the resist mask patterns215A and 215B, the second mask layer 210 is patterned by using dryetching. After the resist mask patterns are removed, the first masklayer 205 is patterned, thereby obtaining hard mask patterns 210A/205Aand 210B/205B, as shown in FIGS. 25A and 25B.

Subsequently, by using hard mask patterns 210A/205A and 210B/205B asetching masks, the third conductive layer 200 is etched, therebyobtaining word lines 200A and an erase gate line 200C in thenon-volatile memory area, and a gate electrode 200B in the logic circuitarea.

As shown in FIG. 26A, in the non-volatile memory area, the erase gateline 200C disposed between two adjacent gate stack structure 50 and wordlines 200A are disposed such that one of the word lines, one of the gatestack structures, the erase gate line, the other of the gate stackstructures and the other of the word lines are arranged in this orderalong the Y direction. At least one of the word lines includes aprotrusion 220, as shown in FIG. 26A. A height of the protrusion 220from the substrate (active region) 10 is higher than a height of theerase gate line 200C from the substrate. In certain embodiments, aheight of the protrusion 220 from the substrate is higher than a heightof the uppermost insulating layer 30 of the gate stack structure 50 fromthe substrate.

Since the word lines 200A, the erase gate line 200C and the gate pattern200B are formed at the same time from the same polysilicon layer, thedopant concentration and polycrystalline structures thereof aresubstantially the same.

In other embodiments, the first mask layer 205 is a BARC layer andresist patterns 215A and 215B are formed on the BARC layer withoutforming the second mask layer 210. In such a case, the BARC layer ispatterned by using the resist patterns and the third conductive materiallayer is patterned by using the patterned BARC layer.

Further in other embodiments, a thin silicon oxide or silicon nitridelayer is formed between the third conductive material layer and theBARC, the thin layer is patterned by using the patterned BARC layer, andthe third conductive material layer is patterned by using the patternedthin layer.

Subsequently, as shown in FIG. 27B, sidewall spacers 230B are formed onboth main side faces of the gate electrode 200B in the logic circuitarea. The sidewall spacers 230B include one or more layers of siliconbased insulating material, such as SiO₂, SiN or SiON. In thenon-volatile memory area, similar sidewalls 230A may be formed on sidefaces of the protrusion 220, as shown in FIG. 27A.

FIGS. 28A and 28B show structures after an interlayer dielectric (ILD)layer 240 is formed. The ILD layer 240 includes one or more layers ofsilicon based insulating material, such as SiO₂, SiN, SiOC, SiCN, SiOCNor SiON.

It is understood that the device shown in FIGS. 28A and 28B undergoesfurther CMOS processes to form various features such as interconnectmetal layers, dielectric layers, passivation layers, etc.

In the embodiment of FIGS. 22A-28B, compared with the embodiments ofFIGS. 12A-21B, four film deposition processes, one lithography process,one etching process and four wet processes can be eliminated. Inparticular, in the embodiment of FIGS. 22A-28B, after the thirdconductive material layer 200 is formed, only one lithography operationis performed to form a gate electrode, word lines and an erase gateline, and only one silicon oxide based material deposition and only onesilicon nitride based material deposition are performed beforepatterning the third conductive material layer.

In the foregoing embodiments, the first to third conductive materiallayers are polysilicon. However, other conductive materials, such asamorphous silicon and metal materials including Cu Al, Ni, W, Ti or Tamay be used.

The various embodiments or examples described herein offer severaladvantages over the existing art. For example, in the presentdisclosure, since one lithography process can define word lines and anerase gate line in a non-volatile memory area and a gate pattern in alogic circuit area, it is possible to reduce process steps andmanufacturing cost.

It will be understood that not all advantages have been necessarilydiscussed herein, no particular advantage is required for allembodiments or examples, and other embodiments or examples may offerdifferent advantages.

In accordance with one aspect of the present disclosure, in a method formanufacturing a semiconductor device, a first and a second stackedstructure of a non-volatile memory are formed over a substrate. Aconductive material layer is formed over the first and second stackedstructures. A planarization layer is formed over the conductive materiallayer. A mask pattern is formed over the planarization layer. Theplanarization layer is patterned by using the mask pattern as an etchingmask. The conductive material layer is patterned, thereby forming anerase gate line between the first and second stacked structure and afirst and a second word line such that the first word line, the firststacked structure, the erase gate line, the second stacked structure andthe second word line are arranged in this order.

In accordance with another aspect of the present disclosure, in a methodfor manufacturing a semiconductor device including a non-volatile memoryarea and a logic circuit area, a first and a second stacked structure ofa non-volatile memory are formed over the non-volatile memory area of asubstrate. A conductive material layer is formed over the first andsecond stacked structures and over the logic circuit area of thesubstrate. A planarization layer is formed over the conductive materiallayer. A first mask pattern is formed on the planarization layer overthe non-volatile memory area and a second mask pattern is formed on theplanarization layer over the logic circuit area. The planarization layeris patterned by using the first and second mask patterns as an etchingmask. The conductive material layer is patterned, thereby forming anerase gate line between the first and second stacked structure and afirst and a second word line in the non-volatile memory area such thatthe first word line, the first stacked structure, the erase gate line,the second stacked structure and the second word line are arranged inthis order, and forming a gate pattern in the logic circuit area.

In accordance with another aspect of the present disclosure, asemiconductor device includes a non-volatile memory and a logic circuit.The non-volatile memory includes a stacked structure comprising a firstinsulating layer, a floating gate, a second insulating layer, a controlgate and a third insulating layer stacked in this order from asubstrate; an erase gate line; and a word line. The logic circuitincludes a field effect transistor comprising a gate electrode. The wordline includes a protrusion, and a height of the protrusion from thesubstrate is higher than a height of the erase gate line from thesubstrate. The word line and the gate electrode are formed ofpolysilicon.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A semiconductor device including a non-volatilememory, wherein: the non-volatile memory includes: a stacked structurecomprising a first insulating layer, a floating gate, a secondinsulating layer, a control gate and a third insulating layer stacked inthis order from a substrate; first sidewalls made of a first dielectricmaterial and disposed over opposing side faces of the stacked structure;an erase gate line; and a word line, the word line includes aprotrusion, and an upper portion of one of the first sidewalls locatedat a word line side is exposed from the word line.
 2. The semiconductordevice of claim 1, wherein a height of the protrusion from the substrateis higher than a height of the erase gate line from the substrate. 3.The semiconductor device of claim 1, wherein: the stacked structurefurther includes second sidewalls made of a second dielectric materialand disposed over opposing side faces of the stacked structure such thatthe second sidewalls are located between the first sidewalls and thestacked structure, and a height of one of the second sidewalls locatedthe word line side is higher than a height of the one of the firstsidewalls located at the word line side.
 4. The semiconductor device ofclaim 3, wherein: the second sidewalls are disposed on opposite sidefaces of the control gate and the third insulating layer, and the firstsidewalls are disposed on opposite side faces of the floating gate. 5.The semiconductor device of claim 1, wherein: the word line includes afirst base portion and a second base portion, the protrusion is disposedbetween and protrude from the first base portion and the second baseportion, and a height of the first base portion is different from aheight of the second base portion.
 6. The semiconductor device of claim5, wherein: the second base portion is disposed closer to the erase gatethan the first base portion, and the height of the first base portion issmaller than the height of the second base portion.
 7. The semiconductordevice of claim 5, wherein a third sidewall made of an insulatingmaterial is disposed on a side face of the first base portion includes.8. The semiconductor device of claim 7, wherein fourth sidewalls made ofthe insulating material are disposed on opposite side faces of theprotrusion.
 9. The semiconductor device of claim 7, wherein the thirdsidewalls and one of the fourth sidewalls of the protrusion locatedcloser to the first base portion than the second base portion arediscontinuous.
 10. The semiconductor device of claim 1, wherein an uppersurface of the protrusion inclines downward toward the stackedstructure.
 11. The semiconductor device of claim 1, wherein a height ofthe protrusion from the substrate is higher than a height of the controlgate from the substrate.
 12. A semiconductor device including anon-volatile memory, wherein: the non-volatile memory includes: a firststacked structure and a second stacked structure, each comprising afirst insulating layer, a floating gate, a second insulating layer and acontrol gate stacked in this order from a substrate; first sidewallsdisposed over opposing side faces of the first stacked structure; secondsidewalls disposed over opposing side faces of the second stackedstructure; an erase gate line disposed between the first stackedstructure and the second stacked structure; and a first word line and asecond word line disposed such that the first stacked structure isdisposed between the first word line and the erase gate line and thesecond stacked structure is disposed between the second word line andthe erase gate line, the first word line includes a first protrusion andthe second word line includes a second protrusion, an upper portion ofone of the first sidewalls located at a first word line side is exposedfrom the first word line, and an upper portion of one of the secondsidewalls located at a second word line side is exposed from the secondword line.
 13. The semiconductor device of claim 12, wherein a height ofthe protrusion from the substrate is higher than a height of the erasegate line from the substrate.
 14. The semiconductor device of claim 12,wherein the protrusion includes sidewall spacers made of an insulatingmaterial.
 15. The semiconductor device of claim 12, wherein: each of thefirst and second word lines includes a first base portion and a secondbase portion, the protrusion is disposed between and protrude from thefirst base portion and the second base portion, and a height of thefirst base portion is different from a height of the second baseportion.
 16. The semiconductor device of claim 15, wherein: the secondbase portion is disposed closer to the erase gate than the first baseportion, and the height of the first base portion is smaller than theheight of the second base portion.
 17. The semiconductor device of claim15, wherein a third sidewall made of an insulating material is disposedon a side face of the first base portion.
 18. The semiconductor deviceof claim 17, wherein: fourth sidewalls made of the insulating materialare disposed on opposite side faces of the protrusion, and the thirdsidewall and one of the fourth sidewalls located closer to the firstbase portion are discontinuous.
 19. The semiconductor device of claim12, wherein an upper surface of the protrusion inclines downward towardthe stacked structure.
 20. A semiconductor device including anon-volatile memory and a logic circuit, wherein: the non-volatilememory includes: a stacked structure comprising a first insulatinglayer, a floating gate, a second insulating layer, a control gate and athird insulating layer stacked in this order from a substrate; firstsidewalls made of a first dielectric material and disposed over opposingside faces of the stacked structure; an erase gate line; and a wordline, the logic circuit includes a field effect transistor comprising agate electrode, the word line includes a protrusion, an upper portion ofone of the first sidewalls located at a word line side is exposed fromthe word line, and the word line and the gate electrode are formed ofpolysilicon.